The present invention is generally directed to radomes and is particularly directed to improving the transmittance bandwidth of radomes having thin dielectric strips on a wall of the radome for compensating for the polarization dependent phase delay of the radome.
A radome is a housing that protects a radar antenna from the elements and does not block radio frequencies. A radome typically includes a dielectric material sheet defining a shell. For radomes installed on the nose of a missile or aircraft, the shell is conical or ogival in shape. The term "conical", as used herein, refers to both conical and ogival shapes. The typical radome shell has a nearly constant thickness that is chosen for transmittance bandwidth and that varies slightly to reduce boresight error.
U.S. Pat. No. 3,576,581, issued Apr. 27, 1971 to the inventors herein, describes a radome having a dielectric material sheet defining a conical shell having an array of thin dielectric material strips supported edgewise on the inside wall of the sheet with the edges of the strips being in contact with the sheet. The array of strips provides anisotropy favoring either parallel or perpendicular polarization components of incident radiation, and thereby compensates the polarization dependent phase delay of the radome shell to reduce sidelobe levels and boresight error while increasing power transmittance. Two alternative preferred embodiments of the arrays of strips are described in U.S. Pat. No. 3,576,581. In one such embodiment, the strips are equally spaced from each other, and disposed so that the intersection of lines extending therefrom is at the vertex of the shell, thereby providing anisotropy favoring parallel polarization components of incident radiation. In the alternative embodiment, the strips are circular rings having their axes along the axis of the shell, thereby providing anisotropy favoring perpendicular components of incident radiation.
It is an object of the present invention to increase the transmittance bandwidth of radomes including such strips.